How to add a text box onto a new page

First, click the thumbnail on the page before where you would like your blank page to appear.

Next, Click the plus "+" symbol in the bar in the top left corner as indicated below in the red box. This will insert a blank page into your book.

To insert a text box, click the text box symbol.

On the page, hold down and drag your pad across the page to create a text box (highlighted in blue)

Click in the box and start typing.